"What's the Name of That Song?" was first performed by the Sesame Street cast in Episode 0666. It has been performed many times since.
It is best known for its recurring "la-di-da-di-dum"'s .

The cast sang this in the finale of Sing Along, and it was also used as a plotline in the self-titled What's the Name of That Song?, in which Oscar the Grouch played an instrumental version of this tune, causing Big Bird to struggle to find out the name of the song. By the end of the video, Grover revealed that this was his favorite song (though he initially didn't know the title either), and then the cast sang this song.